A variety of techniques are utilized in the oil and gas field when creating a new borehole or well. Drilling techniques may vary depending on the type of formation, the location of the rig, the product to be extracted, etc. During formation of the borehole, a well-bore plan, or other previously designed plan for drilling the borehole, is implemented via a computing system or human operations, in conjunction with the borehole assembly, to ensure accurate drilling measurements. Accurate drilling measurements ensure that the reservoir of product, such as oil and/or gas, is reached during the drilling process.
The borehole assembly may include a directional tool, such as a Measurement While Drilling (MWD) tool, often having internal computers that use accelerometers and magnetometers to determine the direction of the tool heading, otherwise referred to as the high-side of the tool. A downhole tool, such as a drilling motor, mud motor, or any other suitable downhole tool, may also be utilized. The downhole tool may include a bent housing located at a bottom end of the tool, such as the bottom end of the drilling motor.
While the downhole tool does not have computer technology within itself, it may be attached to the directional tool during drilling operations. The directional tool may operate according to the well-bore plan, thereby controlling the direction of the downhole tool according to the well-bore plan. When the directional tool and downhole tool are attached, the heading of the directional tool and the heading of the downhole tool may be different. The heading of the various drilling tools may be indicated by a high-side marking, or other indicator, that is marked on the exterior of the drilling tool.
The offset between the directional tool heading and the downhole tool heading, referred to as the angular offset or scribe line offset (SLO), needs to be accounted for and provided to the computing device, or employee, controlling the well-bore plan to ensure accurate drilling. If the SLO is not accounted for, the drilling measurements may have inaccuracies that can lead to drilling issues and mistakes, such as missing the product reservoir, leading to costly time delays and even abandonment of the borehole.
Conventional techniques for calculating the SLO are often left to human approximations. For example, conventional techniques include a rig employee using line of sight to roughly estimate the SLO. An employee may stand at the base of the downhole tool, beneath a directional tool suspended above, and estimate the SLO between a high-side marking indicating the heading of the directional tool and a high-side marking indicating the heading of the downhole tool. This method of calculating the SLO leaves room for significant human error as little accuracy can be ensured using human estimations alone. For example, a drilling employee may be standing at a distance of seventy feet, or longer, below the high-side marking of the directional tool, making it very difficult to visually estimate the offset between the heading of the directional tool and the heading of the downhole tool. Mistakes in the directional-drilling measurements can lead to problems drilling the wellbore, and even abandonment, resulting in costly and time-consuming setbacks.
In addition, safety issues can also be of concern. The drilling environment can be filled with many hazardous conditions related to drilling machinery and operations. For example, requiring that an employee stand below a suspended MWD during drilling operations can lead to increased risk of human injury.